One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,8)(4,6)(5,7)(9,10,14,11)(12,15,20,17)(13,18,22,16)(19,24,21,23)(25,26)(27,32)(28,38)(29,34)(30,39)(31,33)(35,37)(36,40)(1,3,5,6)(2,4,7,8)(10,11)(15,17)(16,18)(23,24)(25,27,31,36)(26,32,33,40)(28,30,34,37)(29,35,38,39)(10,11)(15,17)(16,18)(23,24)(26,33)(27,36)(28,34)(35,39) involution — undirected(1,2)(3,8)(4,6)(5,7)(9,11,14,10)(12,17,20,15)(13,18,22,16)(19,24,21,23)(25,28,31,34)(26,29,33,38)(27,37,36,30)(32,39,40,35)(1,4,5,8)(2,6,7,3)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,29)(26,34)(27,35)(28,33)(30,40)(31,38)(32,37)(36,39)(1,2)(3,4)(5,7)(6,8)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)(25,30,31,37)(26,35,33,39)(27,34,36,28)(29,32,38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.